In a nationwide cohort study, scientists in Denmark investigated the association between residential road traffic and railway noise exposure, measured both at the least and the most exposed façades, and risk of incident tinnitus. The study was based on individual-level information on hearing-related diagnoses, address history, and socioeconomic factors.
Cantuaria et al. found positive associations between exposure to road traffic noise and risk of tinnitus; highest risk estimates were found for women, people without a hearing loss, people with high education and income, and people who had never been in a blue-collar job. Image credit: Pexels.
Transportation noise is increasingly recognized as harmful to human health, being a growing source of concern among the general population.
In Europe, more than 100 million people are exposed to transportation noise above the Environmental Noise Directive threshold of 55 dB.
Transportation noise exposure is believed to be detrimental to human health through stress reactions with activation of the hypothalamic-pituitary-adrenal axis, followed by increased levels of stress hormones. In addition, nighttime noise exposure can impact sleep quality and duration, which are crucial for physiological and mental restoration.
Despite emerging knowledge, the extent of health impacts from transportation noise is still not clear; e.g., the WHO stated in 2018 that there was a lack of studies investigating transportation noise and hearing-related outcomes, such as tinnitus, even though these are considered critical outcomes for the development of guidelines regarding health effects of noise.
Tinnitus is a very common disorder characterized by the perception of sound in the ears or head in the absence of an external sound source.
Epidemiological studies worldwide have reported the tinnitus prevalence to range between 5% and 43%.
However, there is no standard criterion for tinnitus diagnosis, and the heterogeneity of the disease in terms of severity and impact is substantial.
Although many people can habituate to it, others are severely affected by the disorder even after seeking medical treatment.
Hearing loss and other otological conditions affecting the middle ear are main risk factors for tinnitus.
However, although cochlear damage is often the origin of tinnitus, the central nervous system is believed to play an important role in the onset and persistence of the disorder.
Tinnitus is considered a stressor per se, leading to increased physiological arousal and psychological distress.
Nevertheless, several studies also suggest a reverse mechanism, where stressful situations and sleep disturbances precede tinnitus occurrence and contribute to the transition from mild to severe symptoms.
“As stress and sleep disturbance are proposed key mechanisms behind the harmful effects of noise, we hypothesize that transportation noise can affect onset and severity of tinnitus,” said Dr. Manuella Lech Cantuaria, a researcher at the University of Southern Denmark and the Danish Cancer Society Research Center, and colleagues.
“However, to the extent of our knowledge, no longitudinal studies have investigated the effect of residential transportation noise on tinnitus or other auditory outcomes.”
The authors performed a nationwide cohort study, including all residents age over 30 years living in Denmark between January 2000 and December 2017, and born after 1920.
“In our data, we found 40,692 cases of tinnitus and can see that for every 10 dB more noise in people’s home, the risk of developing tinnitus increases by 6%,” Dr. Cantuaria said.
“There is a need for more focus on the importance of traffic noise for health,” said Dr. Jesper Hvass Schmidt, a researcher at the University of Southern Denmark and Odense University Hospital.
“It is alarming that noise seems to increase the risk of tinnitus, cardiovascular diseases and dementia, among other diseases.”
The researchers believe that noise at nighttime can be even worse for health. It affects our sleep, which is so important for restoring both our physical and mental health.
“There are different things one can do to reduce noise in their homes, for example by sleeping in a room that does not face the road or by installing soundproof windows. But not everyone has those options,” Dr. Cantuaria said.
“It is therefore necessary that traffic noise is considered a health risk that must be taken into account in urban planning and political decisions.”
The findings appear in the journal Environmental Health Perspectives.
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Manuella Lech Cantuaria et al. 2023. Transportation Noise and Risk of Tinnitus: A Nationwide Cohort Study from Denmark. Environmental Health Perspectives 131 (2); doi: 10.1289/EHP11248
